Buildings, including houses, office buildings, strip malls and the like, are often constructed such that a building frame rests on a foundation. Foundation types are generally known and can include concrete slabs, reinforced concrete slabs, pier-and-beam, footings, and other types. Sometimes foundations include structures that are deep enough to contact, or tie into, solid strata such as bedrock. Other foundations are made shallow and rest on soil above the bedrock. These foundations may include structures, such as concrete slabs for example, that distribute the weight of the building across a relatively large area of the soil.
Changing soil conditions and/or improper building construction can result in portions of the building sagging or drooping. This can be caused by parts of the foundation sinking where the soil conditions are insufficient to support the structure. The sagging and drooping can, in turn, cause damage to the frame, drywall, flooring, plumbing, and other components of the building.
When a foundation structure such as a slab sinks, it becomes necessary to raise the sinking portion and support it such that it does not re-settle or sink further. Prior techniques have involved jacking up the slab and positioning pilings below the foundation for support. However, the pilings are not in contact with the solid strata, so additional foundation sinking can still occur. Additionally, these techniques can be very expensive and can be visually unpleasing as the repair components such as the pilings are typically visible after the repair work is completed.
Moreover, sometimes a foundation needs support within the perimeter boundaries of the foundation and in an area that is not easily reached from outside the edges of the foundation. For example, with a concrete slab foundation, support is sometimes needed in an area within the slab boundaries. In certain areas such as this, supporting an edge of the slab is not sufficient. And, reaching certain interior areas from the exterior of the structure over the foundation, or from the outer edges of the foundation, may involve extensive excavation. This may include substantial drilling and tunneling underneath the structure, from the outside or outer edges, to reach the area that needs support. This can be cost-prohibitive. Prior methods have involved drilling a hole through the foundation, inserting a support device and raising the support device to support the slab. Once such prior method, as disclosed in U.S. Pat. No. 7,780,376 issued to Bracken et al., involves the use of a relatively complex support bracket. The bracket has a sleeve through which a support shaft is positioned. The bracket also includes a number of arms that move from a retracted position to an extended position. The bracket is inserted through the foundation hold with the arms in the retracted position. The arms are then adjusted to the extended position and the bracket is moved upward to engage the foundation.
Retraction and extension of the arms, however, is relatively complex. To adjust the arms to the retracted position, an adjustable collar around the support shaft is moved downwardly. This is accomplished by downward movement of a plate support that is coupled to the collar by way of several threaded rods. The downward motion of the collar pulls on linkage arms that are connected to the underside of the support arms, thereby pulling the outer ends of the support arms in a downward direction. When the bracket is in the foundation hole, the plate support is lifted to pull up the collar, thereby forcing up the outer ends of the support arms into an extended position. The plate support must be fixed on the threaded arms. Then a hydraulic ram may be used to lift the bracket, and thereby lift the support arms upwardly against the bottom of the foundation.